Bump @wordpress/eslint-plugin from 18.1.0 to 21.4.0 (#630)

Bumps [@wordpress/eslint-plugin](https://github.com/WordPress/gutenberg/tree/HEAD/packages/eslint-plugin) from 18.1.0 to 21.4.0.
- [Release notes](https://github.com/WordPress/gutenberg/releases)
- [Changelog](https://github.com/WordPress/gutenberg/blob/trunk/packages/eslint-plugin/CHANGELOG.md)
- [Commits](https://github.com/WordPress/gutenberg/commits/@wordpress/[email protected]/packages/eslint-plugin)

---
updated-dependencies:
- dependency-name: "@wordpress/eslint-plugin"
  dependency-type: direct:development
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

Diff for: package.json

@@ -1,7 +1,7 @@
 {
   "private": true,
   "devDependencies": {
-    "@wordpress/eslint-plugin": "^18.1.0",
+    "@wordpress/eslint-plugin": "^21.4.0",
     "@wordpress/stylelint-config": "^21.36.0",
     "eslint": "^8.57.0",
     "prettier": "^3.2.5",